Fix test not passing

Signed-off-by: qcabrol

Author: cabrol

dissect/cstruct/cstruct.py

@@ -81,7 +81,7 @@ def _read(self, stream):
 
         return Instance(self, r, sizes)
 
-    def add_fields(self, name, type_, offset=None, commentAttributes={}):
+    def add_fields(self, name, type_, offset=None, commentAttributes={{}}):
         raise NotImplementedError("Can't add fields to a compiled structure")
 
     def __repr__(self):